Democratic U.S. Sen. Tammy Baldwin will air her first TV ads Tuesday in her re-election campaign, highlighting "Buy America" legislation and work on prescription drug costs.

The 30-second ads will be broadcast in the Milwaukee and Green Bay markets and will also be presented on digital sites, her campaign said.

Baldwin, a first-term senator, faces a strong challenge from state Senator Leah Vukmir of Brookfield and Delafield businessman Kevin Nicholson, who are fighting for the Republican nomination.

Baldwin's Republican rivals have not yet aired their own ads. But outside groups have already spent at least $3.1 million against her in what is expected to be among the expensive Senate races in the country.

In the ads, Baldwin hits on themes that appear to have bipartisan support.

One ad features former Neenah Foundry worker Roddy Rice and focuses on Baldwin's push for "Buy America" legislation to require American-made materials in water infrastructure projects.

"My Buy America legislation requires government infrastructure projects to use 100 percent American iron and steel, because it's time America buys what Wisconsin makes," Baldwin says in the ad.

Brandon Moody, a spokesman for the Nicholson campaign, criticized the ads.

“For a senator who consistently ranks among the most liberal in Washington, Tammy Baldwin’s attempts at bipartisanship are laughable," he said in a statement.

"Her second ad features John McCain as much as herself which just goes to show how desperate she is to cling to anything that shows she’s worked with Republicans. The truth is, she hasn’t. And we all know she never will."